(Vienna, 22 May-2026) A multidisciplinary research team at the Medical University of Vienna has created a comprehensive cell atlas of the human thymus, thereby gaining new insights into the development and biological differences of rare thymus tumours. The study, published in Nature Communications, presents the analysis of a total of 453,727 individual cells from 53 datasets and the first systematic comparison between healthy thymus tissue at different stages of life and various pathological changes such as thymic hyperplasia and thymic tumours. The results lay the groundwork for a better understanding of these rare diseases and could, in the long term, contribute to the development of precise diagnostic and therapeutic approaches.
The thymus is a central organ of the immune system and plays a crucial role in the maturation of T cells, which are responsible for targeted immune defence. Whilst the organ normally regresses over the course of a lifetime, pathological changes can occur in rare cases. These include thymus tumours, which originate from the organ’s epithelial cells, as well as thymic hyperplasia, in which the thymus functions normally but in an enlarged form. Due to their rarity, the molecular causes of these diseases have so far remained poorly understood. Significant new findings have now been obtained as part of the current MedUni Vienna publication: "The cell atlas we have created provides, for the first time, a detailed systematic overview that will enable pathological changes in the thymus to be precisely classified in future," says co-study leader Hendrik Jan Ankersmit (Department of Thoracic Surgery, MedUni Vienna), summarising the relevance of the research.
Detailed analysis at the single-cell level
To create the cell atlas, the research team used single-cell RNA sequencing, a technique that allows the gene activity of individual cells to be analysed precisely. In doing so, the researchers identified specific changes in thymic epithelial cells, which are essential for the development of T cells, as well as in fibroblasts—connective tissue cells that help shape the structure of the organ. The single-cell analysis also revealed two cell populations that had not been detected in previous studies. These are specific types of epithelial cells and fibroblasts that occur almost exclusively in tumour tissue and activate genetic programmes associated with tissue remodelling and developmental processes. "This newly acquired knowledge allows us to understand the biological differences between the individual tumour types much better," says lead author Martin Direder-Scheiber (Department of Orthopedics and Trauma-Surgery, MedUni Vienna). The study results also show that the various tumour subtypes are underpinned by molecular mechanisms that are partly overlapping and partly distinct. "This is an essential prerequisite for diagnosing these diseases in a more differentiated manner and treating them in a targeted way in the future," explains co-study leader Michael Mildner (Department of Dermatology, MedUni Vienna).
Thymic tumours are among the rarest tumour diseases and account for less than one per cent of all malignant tumours in the chest cavity. They occur in the anterior mediastinum, the space between the lungs, and are often discovered by chance. The data now available make an important contribution to a better understanding of these diseases and their distinction from benign changes such as thymic hyperplasia. "As the thymus plays a key role in the development of the body’s immune system, our detailed insights may also open up new avenues for immunological research," emphasises co-author Bernhard Moser (Department of Thoracic Surgery, MedUni Vienna).
Basic research into thymus pathology has been financially supported at the Department of Thoracic Surgery at MedUni Vienna since 2010 by the CD Laboratory for the Diagnosis and Regeneration of Heart and Thoracic Diseases (2009–2014) and APOSCIENCE AG. "The successful cooperation between public and private interests (Public-Private Partnership, PPP) represents an alternative to conventional funding bodies for defining medically relevant research questions in the field of rare diseases. The understanding and potential of the link between basic research and surgery were recognised in this project and have made this important publication possible," emphasises Hendrik Jan Ankersmit.
Publication: Nature Communications
A single-cell atlas revealing cellular heterogeneity across healthy and diseased human thymus.
Martin Direder, Matthias Wielscher, Melanie Salek, Maria Laggner, Dragan Copic, Katharina Klas, Daniel Bormann, Bahar Golabi, Hannes Kühtreiber, Marie-Therese, Lingitz, Leonhard Müllauer, Ana-Iris Schiefer, Wolfgang Weninger, Clemens Aigner, Hendrik Jan Ankersmit, Michael Mildner & Bernhard Moser.
https://doi.org/10.1038/s41467-026-72760-7